The present controversy over the UK’s decision not help refugees and migrants from North Africa and the Middle East at risk from drowning as they seek a better life in Europe, highlights a significant and growing global problem: what to do with thousands of displaced – forced or voluntary – people?

It has gone largely unremarked that Curiosity’s latest pictures show a network of valleys formed by flowing water, indicating there was physical life there once – and hinting at significant parallels with Earth.